scholarly journals Molecular Weight of Agar by High Temperature Type Gel Permeation Chromatography and Physical Properties.

1999 ◽  
Vol 46 (12) ◽  
pp. 821-826 ◽  
Author(s):  
Hisashi SUZUKI ◽  
Yoshinori SAWAI ◽  
Mitsuro TAKADA
Keyword(s):  
Molecular Weight ◽  
High Temperature ◽  
Physical Properties ◽  
Gel Permeation Chromatography ◽  
Gel Permeation

The High Temperature Gel Permeation Chromatography Study on Poly (Phenylene Sulfide) Linear Chain Propagation

2010 ◽  
Vol 139-141 ◽  
pp. 661-665
Author(s):  
Yu Zhou ◽  
Bo Wen Cheng ◽  
Zhen Huan Li ◽  
De Xin Shen ◽  
Sheng Zhang ◽  
...  
Keyword(s):  
Molecular Weight ◽  
High Temperature ◽  
Sodium Sulfide ◽  
Linear Chain ◽  
Gel Permeation Chromatography ◽  
Chain Propagation ◽  
Chain Growth ◽  
Gel Permeation ◽  
Methyl Pyrrolidone ◽  
Phenylene Sulfide

A linear and high molecular weight poly(phenylene sulfide) (PPS) was synthesized from P-dichlorobenzene (P-DCB) and anhydrous sodium sulfide in N-methyl pyrrolidone (NMP), and the High Temperature Gel Permeation Chromatography (HTGPC) technique was utilized to investigate the effects of reaction condition on PPS chain propagation. The experiment results indicated that the high pro-reaction temperature or high post-temperature would interfere with PPS chain propagation, and post-reaction time was another important factor to influence PPS molecular weight (Mw) extension. Furthermore, the optimized ratio of high Mw PPS polymer synthesis was typically at 3-6% molar excess of Na2S over p-dichlorobenzene, and N-methyl-2-pyrrolidone (NMP) were beneficial to the production of high Mw PPS due to the formation of sodium 4-(N-methylamino) butanoate (SMAB). The alkaline reagents such as Na3PO4 and K3PO4 et al could capture the H of -SH, which changed -SH into -SNa and promoted the chain growth of PPS to achieve extension.

New Thermoplastic Elastomers. Styrene Grafts on Lithiated Polydienes and Their Hydrogenated Counterparts

1973 ◽  
Vol 46 (4) ◽  
pp. 1044-1054 ◽  
Author(s):  
J. C. Falk ◽  
R. J. Schlott ◽  
D. F. Hoeg ◽  
J. F. Pendleton
Keyword(s):  
Molecular Weight ◽  
Physical Properties ◽  
Room Temperature ◽  
Graft Copolymers ◽  
Gel Permeation Chromatography ◽  
Thermoplastic Elastomers ◽  
Proper Choice ◽  
Melt Flow ◽  
Gel Permeation ◽  
Poly Ethylene

Abstract Metalation of diene polymers such as poly (butadiene) and poly(isoprene) with sec-butyllithium and tetramethylethylenediamine in cyclohexane at room temperature forms lithiated polydienes. Reaction of the polylithiodienes with styrene or α-methylstyrene forms graft copolymers. The extent of metalation is much greater than previously reported metalations with n-butyllithium and tetramethylethylenediamine. The grafting efficiencies, determined by acetone extraction and gel permeation chromatography, are greater than 95 per cent. Graft copolymers of poly (styrene) on EPDM rubbers may also be prepared using this technique. The physical properties of the graft copolymers are a function of molecular weight, graft site level, and composition. Products at specific compositions and graft levels are thermoplastic elastomers. Their properties are comparable to SBS rubbers, and offer as an advantage high melt flow. Graft copolymers of poly(styrene) on poly(ethylene) and poly(ethylene-co-butene-1) result from the hydrogenation of the butadiene moeities of graft copolymers of poly (styrene) on 1,4-poly(butadiene) and 1,2 and 1,4-butadiene copolymers, respectively. Complete hydrogenation results in graft copolymers of poly(vinylcyclohexane) on poly(ethylene) and on poly(ethylene-co-butene-1). In both of these cases thermoplastic elastomers result if the proper choice of composition and graft level is made.

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